Heating or power generating systems utilizing solar energy are well known and have recently become much more widely used with the recognition of an energy shortage and the correspondingly increased interest in development of alternative energy sources. Various configurations of solar energy systems have been employed and generally are quite intricate and expensive, including those using reduced pressure to affect vaporization of a fluid.
Exemplary of this latter type of system is U.S. Pat. No. 991,161 granted on May 2, 1911 to E. H. McHenry. This system, however, does not maintain a reduced pressure within the solar panels but has a separate expansion chamber, thereafter using the vapor generated to drive a motor. Furthermore, his device has no means responsive to the temperature of the solar panels to effect automatic activation of the system when the solar panel temperature is high enough to ensure vaporization and to drain the panels when the temperature thereof falls below the freezing point of the liquid used.
Accordingly, it is an object of the present invention to provide a novel solar heating system which is relatively simple and relatively economical to manufacture and wherein the solar panels are maintained at a reduced pressure to facilitate vaporization of the fluid used and subsequent utilization of the latent heat of vaporization of such fluid.
It is also an object to provide such a solar heating system which operates automatically in response to the temperature sensed at the solar panels and that sensed in the fluid of a secondary system to which heat is transferred for utilization as desired.
Another object is to provide such a solar heating system wherein the solar panels are automatically drained if the temperature thereof falls below a preset value.